1. Field of the Invention
The present invention relates to multi-layer woven fabrics, and more particularly to fabrics having a first yarn system arranged into plural yarn layers between opposite broad surfaces of the fabric and a second yarn system extending through the thickness of the fabric between the opposite broad surfaces and being interwoven with the yarn layers.
2. Description of the Prior Art
It is known in the art of multi-layer woven materials to weave a fabric from a plurality of different yarn systems which provide the fabric with multiple interwoven layers or plies of thickness. Fabrics of this type can be woven using a circular loom such that the fabrics have an essentially circular makeup or configuration. Fabrics of that type are illustrated by U.S. Pat. No. 3,749,138 of Rheaume et al, which patent issued July 31, 1973 and is commonly assigned with the present application. The Rheaume et al patent describes the weaving of a multi-layer fabric which is comprised of angled warp yarns extending through the thickness of the fabric and interwoven with fill yarns which extend along the length of the fabric in an orientation generally parallel to one another and to the opposite broad surfaces of the fabric and perpendicular to the warp yarns. A third or stuffer yarn system may be present such that generally parallel stuffer yarns extend across the width of the fabric in orientations perpendicular to the fill yarns.
Multi-layer fabrics may also be woven in a noncircular configuration such as in other curved configurations or in a generally rectangular configuration using conventional weaving apparatus. An example of such woven configurations is provided by U.S. Pat. No. 4,312,913 of Rheaume, which patent issued Jan. 26, 1982. The Rheaume patent illustrates fabric produced by an angle weave in which lengths of fill yarn disposed in a nominally parallel configuration are interwoven with angled warp yarns. The warp yarns extend in a zig-zag configuration through the thickness of the fabric between the opposite broad surfaces thereof so as to form a succession of intersecting warp sheets. The warp sheets intersect with and form acute angles with the opposite broad surfaces of the woven fabric and with yarn layers formed by the fill yarns.
The multi-layer woven fabrics described in U.S. Pat. No. 3,749,138 of Rheaume et al and U.S. Pat. No. 4,312,913 of Rheaume are typical of woven angled fabrics in which the warp yarn system extends through the entire thickness of the fabric to provide an integral, tightly woven multi-layer fabric having generally uniform properties throughout the thickness thereof. Such structures are advantageous for many applications calling for multi-layer fabrics with good structural and other properties. However, it may be desirable for certain applications to provide alternate forms of multi-layer angle interlock fabrics and methods of making them in order to achieve other structural configurations or advantages For example, it may be advantageous to provide a multi-layer fabric in which one of the yarn systems extends in relatively straight fashion along the length of the fabric as woven to provide the fabric with substantial strength in the length direction. By way of further example it may be advantageous to provide a multi-layer woven fabric having a slot therein extending across a portion of the width of the fabric and along the length of the fabric.